A camera is very similar to our eyes. When we see things, our eyes see it upside down. Then our brain automatically flips it around to show what we are seeing. The same thing happens in a camera. Here is an image to show this.
Both a camera and an eye have sensors which can detect how much light is being let in and if it is too much or too little. Lenses don't change shape, they move closer or further away to the light sensor to make the camera zoom in and out. Aperture in the lens is what controls the amount of light that is able to reach the sensor. The shutter within the camera also opens and closes to let the right amount of light into the camera and onto the sensor, if these settings are all correct the the image you take should be the correct exposure.
ISO - ISO is the sensitivity to light. The lower the number is for the ISO setting, the less sensitive the camera is to light. This means that if the number is too low the image will be very dark and if the number is too high then the image will have a grainy effect which is what should be avoided unless you need a grainy styled photo.
Shutter Speed - Shutter speed is the time it takes for the shutter to open to close and for it to let in light. The slower the shutter speed, the more light is able to get in. If this happens then motion blur will occur.
Aperture - The aperture controls the depth of field. The aperture is a hole in the camera that can be changed to let more/less light into the camera. The smaller that the hole is then the lower amount of light let into the camera and also the larger the depth of field. The bigger the whole, the shallower the depth of field will be and more light will be allowed in.
If you want a well exposed image then all of the 3 settings above must be at the right amount.
Composition is the positioning of the subject within the image. For example we use rule of thirds which is a grid on the photo and you place the main focus of the image in one of the corners of the grid. The grid splits up the image into 9 different sections. Another technique used in photography is framing. This is where you find a natural frame to the subject. For example taking a photo through a window would be a use of framing. Another technique is guiding the person looking at the image to the subject of that image. An example of this would be a fence going through the image and when you look at that fence it leads you to the main focus of that image.
To show all of the different things you can do with lighting we did a small practice on an egg. We had a lamp and an egg and we had to move the lamp around to show what effects we can make with lighting, here are the images.